Printing Flexible Electronics for health care Applications
Pit Teunissen
Eric Rubingh
Ruben Lelieveld
Marc Koetse
Juliane Gabel
Pim Groen
Printed and organic electronics
November 20, 2014
Presentation overview
Printing Flexible Electronics for health care Applications, Pit Teunissen
1. Introduction smart blister
2. Device architecture
3. Way of working
4. Results
5. Towards high volume production
6. Conclusions
7. Outlook
© Holst Centre
Smart Blister
• Pharmaceutical package capable of monitoring when a pill is taken out of its packaging
• Data can easily be transferred wireless via NFC
• Main purpose: To ensure that patients in clinical trials take their medicine at the time and frequency recommended to avoid non-compliance issues
Printing Flexible Electronics for health care Applications, Pit Teunissen
© Holst Centre
Smart blister: Partner request
Printing Flexible Electronics for health care Applications, Pit Teunissen
• Assembled
• “3D”-system
• High cost
• Added to existing package
• Fully integrated
• 2D-System in Foil
• Low cost, mass fabrication
• Roll to Roll compatible
Request from partner: from assembled PCB to low-cost integrated system in foil
© Holst Centre
Technological challenges
System engineering
• Simplification, cost reduction
• Optimal chip set
• Design rules
Printing
• Conductivity (Antenna)
• Multi layer (circuitry)
• Overlay precision
Assembly
• Adhesives
• Accuracy
• Reliability and durability
Printing Flexible Electronics for health care Applications, Pit Teunissen
Presentation overview
Printing Flexible Electronics for health care Applications, Pit Teunissen
1. Introduction Smart blister
2. Device architecture
3. Way of Working
4. results
5. Towards high volume production
6. Conclusions
7. Outlook
© Holst Centre
Substrate selection
Substrate:
• Price
PI >50€/m2
PEN <10 €/m2
PET <1 €/m2
Printing Flexible Electronics for health care Applications, Pit Teunissen
Preferred substrate PET
• Tg PET ~ 100°C
Processing temperature < 130 °C
© Holst Centre
Building Blocks
Printing Flexible Electronics for health care Applications, Pit Teunissen
sensing
logic
radio
antenna
power Thin film battery
Resistance ladder to monitor which pill was taken from package
Integrated chips for measuring and registration
Printed antenna for data transfer
Integrated chips for RFID communication and data storage
© Holst Centre
Deposition method
Processing:
• High speed processing / large volume
R2R compatible
High speed
Resolution ~100µm features
Multi-layer 100µm overlay accuracy
High aspect ratio for high conductivity
Printing Flexible Electronics for health care Applications, Pit Teunissen
Screen printing
© Holst Centre
Printing Flexible Electronics for health care Applications, Pit Teunissen
Device layers
• Five layers
1: Circuit including antenna
~100µm feature size
Good conductivity
2: Antenna
~100µm overlay accuracy
~100µm feature size
Resistance ≤40 Ω
3: Dielectric
Good insulating properties
Prevent shorts in crossing layers
4: Bridges
Make electrical contact between components
5: Printed resistors
Monitor which pill is taken out
Accurate resistance (< 5% deviation)
© Holst Centre
Printing Flexible Electronics for health care Applications, Pit Teunissen
Components
Components
• 3 chip solution
MC: micro controller (measure and register)
RTC: real time clock (date, time)
NFC Eeprom: RFID communication and data storage
• Thin components
Components can be integrated in foil
• Assembly
No soldering possible!
Use novel low T cure isotropic conductive adhesives (100 °C cure)
without package
thinning chip down to 20-30 µm
chip becomes flexible
Presentation overview
Printing Flexible Electronics for health care Applications, Pit Teunissen
1. Introduction smart blister
2. Device architecture
3. Way of working
4. Results
5. Towards high volume production
6. Conclusions
7. Outlook
© Holst Centre
Way of Working – Deposition method
• Screen printing: principle
Paste is applied in a patterned mesh
Mesh is positioned above substrate
Ink is pushed through the mesh and a direct image of the screen is made on the substrate
Printing Flexible Electronics for health care Applications, Pit Teunissen
smallest feature size (lab)
30 m
smallest feature size (industrial scale)
80 m
ink viscosity range 100 – 800,000 mPas
wet layer thickness 12 – 500 m
dry layer thickness 0.5 – 50 µm
dry layer thickness accuracy
15 – 40 %
alignment/overlay accuracy
100 m
Processing time < 1 min. / sheet
Woven mesh
© Holst Centre
Printing Flexible Electronics for health care Applications, Pit Teunissen
Way of working – Equipment and materials
• S2S screen printer
DEK Horizon 03i
• Mesh technology
Stainless steel woven mesh
Stork Prints PlanoMesh, electroformed Nickel
• Materials
Silver paste (layer 1, 2 and 4)
1: Circuit, including antenna (DuPont 5025)
2: Antenna (DuPont PV410)
4: Bridges (DuPont 5025)
Isolator (layer 3)
3: Dielectric (DuPont 7165)
Carbon (layer 5)
5: Resistors (DuPont 7082 + DuPont 5036)
Stork Prints PlanoMesh
Dek screen printer
© Holst Centre
Printing Flexible Electronics for health care Applications, Pit Teunissen
Way of working – Sintering
• Sintering
Metal nano,- and micro particle need to be dried and/or sintered to become conductive
Sintering = merging particles via atomic diffusion
Fraction of the bulk melting temperature
Nanoparticle inks are ideal for conductive structures on temperature-sensitive substrates
Sintering can be done thermally, photonically, electrically, using plasma, chemically, etc.
Here we use thermal sintering in an oven at 130°C
Sintered Ag nanoparticles
Presentation overview
Printing Flexible Electronics for health care Applications, Pit Teunissen
1. Introduction smart blister
2. Device architecture
3. Way of working
4. Results
5. Towards high volume production
6. Conclusions
7. Outlook
© Holst Centre
Results
Printing Flexible Electronics for health care Applications, Pit Teunissen
• 1st layer: circuit for electrical contacts
Smallest line width: 100µm
Good Conductivity
Typical line height ~6µm
Profile measurement antenna Screen printed circuit
© Holst Centre
Results
Printing Flexible Electronics for health care Applications, Pit Teunissen
• 2nd layer: antenna
Extra layer is printed to improve the conductivity
Resistance 15-16 Ohm (<40 Ohm needed)
SPG PlanoMesh screens are used to print thicker in one step while maintaining resolution
Stork Antenna DuPont 5025 + PV410
-5000
0
5000
10000
15000
20000
25000
30000
35000
40000
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Position (µm)
He
igh
t (n
m)
Profile measurement antenna 2 layers printed using woven mesh
Profile measurement antenna 2 layers printed using plano mesh
© Holst Centre
Results
Printing Flexible Electronics for health care Applications, Pit Teunissen
• 3rd layer: dielectric
Al spikes in Silver should be covered
No pinholes allowed
Back scatter: White Silver; black dielectric Left Silver; right Silver+dielectric
Defect piercing dielectric
© Holst Centre
Results
Printing Flexible Electronics for health care Applications, Pit Teunissen
• 3rd layer: dielectric
Depending on 1st layer, up to 4 layers needed to give optimal isolation
Pinhole in dielectric
Antenna silver lines
Cross section dielectric on Silver
Profile of antenna covered with dielectric
© Holst Centre
Results
Printing Flexible Electronics for health care Applications, Pit Teunissen
• 4th layer: bridges
Challenge is to print high resolution lines on multi layer stack with >30µm step height
Printed 100µm lines on top of 2 layers of silver and 4 layers of dielectric
Dielectric
Silver bridges
Profile of printed silver bridges on top of silver and dielectric
© Holst Centre
Results
Printing Flexible Electronics for health care Applications, Pit Teunissen
• 5th layer: printed resistors
• Results carbon resistors
Resistance accuracy < 5% within one sheet
Practical tests show that with a resistance ladder for 4 different pills pushed out all combinations can be correctly registered (DAC converter behavior)
Low value resistors have larger resistance than designed
A theoretical model was made and showed the same effect
The edges of the large carbon resistors have a relative larger contribution to the conductivity compared with small carbon resistors
© Holst Centre
Results
• Towards lower cost materials
Use printed copper for main circuit and bridges
Antenna is still silver to get the high conductivity needed
Working blisters were made
160°C processing temperature needed
Lifetime not yet good enough
Printing Flexible Electronics for health care Applications, Pit Teunissen
Cross section Copper-dielectric-Copper Smart blister made of screen printed Copper
© Holst Centre
Results
• Current process suits for low volume production
High volume needs continuous production process
Printing Flexible Electronics for health care Applications, Pit Teunissen
4 intermediate generations of smart blister
• Several working devices were made
Components on top Components in blister
Components in blister Components in blister
Final version of smart blister
Presentation overview
Printing Flexible Electronics for health care Applications, Pit Teunissen
1. Introduction smart blister
2. Device architecture
3. Way of working
4. Results
5. Towards high volume production
6. Conclusions
7. Outlook
© Holst Centre
Towards high volume production
Transfer from S2S process to R2R process
• Flatbed screen printing Rotary screen printing
Similar process as flatbed screen printing
Circular formed mesh for continuous production
Printing Flexible Electronics for health care Applications, Pit Teunissen
smallest feature size (lab)
40 m
smallest feature size (industrial scale)
100 m
ink viscosity range 100 – 80,000 mPas
wet layer thickness 12 – 500 m
dry layer thickness 500 – 50,000 nm
dry layer thickness accuracy
15 – 40 %
alignment/overlay accuracy
100 m
linear line speed >> 10 m/min, independent from resolution
© Holst Centre
Printing Flexible Electronics for health care Applications, Pit Teunissen
Towards high volume production
Transfer from S2S process to R2R process
• Thermal sintering Photonic sintering
Selective heating through light absorption by the ink, not by the foil
High energy densities achieved by light focusing with an elliptical reflector
Pulsed light instead of continuous radiation to prevent excessive heating and substrate deformation Reflector geometry
Fast sintering (50 ms) of
development paste
3 flashes of 10 ms
Ref: Abbel et al., MRS Commun., 2012, 2, 145.
© Holst Centre
Printing Flexible Electronics for health care Applications, Pit Teunissen
• Inline temperature and resistance measurement
The temperature profile reveals the change in material properties of the conductive ink. DuPont W693 (Ag development paste) on PEN
Photonic Sintering: Process study
Thermal conductivity: Low Heat capacity: High
Thermal conductivity: High Heat capacity: Low
Tg of PEN
© Holst Centre
Printing Flexible Electronics for health care Applications, Pit Teunissen
• Entrapped solvents, bubbles and ablation
Top illumination: Shell formation
Short pulses: Not suited for drying
Fast heating: Entrapped solvents and exploding bubbles
Solvent evaporation: Back illumination and long pulses
High peak temperatures: Ablation due to polymer degradation
Process study
Shell formation Short pulses
Ablation (pre-dried ink) High peak temperature
Exploding bubbles Fast heating
50 x 50 x SEM, 100 x
© Holst Centre
Printing Flexible Electronics for health care Applications, Pit Teunissen
• Sequence flash sintering (Silver np ink)
To achieve highly conductive structures without deforming the temperature-sensitive substrate, two flash settings are used
Process Time Temperature Pulse settings
Solvent evaporation seconds < Tg low intensity, high frequency
Sintering milliseconds >(>) 250°C high intensity, short pulse(s)
Using NIR pre-drying is a good alternative for the first stage
50x
Photonic sintering – process study
© Holst Centre
Printing Flexible Electronics for health care Applications, Pit Teunissen
• Stand alone photonic sintering unit
Research tool to investigate sintering behavior of conductive inks
Elliptic shaped reflector to focus light
Inline resistance and temperature measurement (4-point)
Nitrogen atmosphere possible (copper inks)
• S2S photonic sintering unit
Research tool to upscale from single line to 30x30 cm
2 side illumination
Up to 10 lamps
Inline resistance and temp.
measurement (4-point)
Photonic sintering: Experimental setup (1)
Stand alone photonic sintering unit
© Holst Centre
Pit Teunissen, The IJC Dusseldorf, September 30, 2014
< 33
Novacentrix PulseForge 1300
Max radiant energy delivered
45 (J/cm2)
Curing dimension per pulse
75 x 150 (mm)
Max area cured per sample
300 x 150 (mm)
Capable of sintering copper materials
Particle based, complexes, oxides
Additional functionality developed at Holst
Inline measurement at 10,000 samples/s
Resistance
Temperature
Functionalities beyond sintering only
Photonic sintering: Experimental setup (2)
© Holst Centre
Rotary screen printing of functional structures: 3 layer stack
1st layer: Circuitry
2nd layer: Isolation
3rd layer: Bridges
Photograph of the R2R system containing the rotary screen printer and the sintering module
R2R rotary screen printing and in-line photonic sintering
Printing Flexible Electronics for health care Applications, Pit Teunissen
Presentation overview
Printing Flexible Electronics for health care Applications, Pit Teunissen
1. Introduction smart blister
2. Device architecture
3. Way of working
4. Results
5. Towards high volume production
6. Conclusions
7. Outlook
© Holst Centre
Conclusions
Printing Flexible Electronics for health care Applications, Pit Teunissen
• Screen printing was demonstrated as a cheap manufacturing method for smart blisters
5 different layers were printed
Good conductivity
Overlay accuracy of ~100µm; even on multi-layer stack
Printed resistance ladders to monitor which pill is removed
Thinned down components integrated in foil
• Rotary screen printing in combination with NIR drying and photonic sintering was shown to be a way for high volume production
Presentation overview
Printing Flexible Electronics for health care Applications, Pit Teunissen
1. Introduction smart blister
2. Device architecture
3. Way of working
4. Results
5. Towards high volume production
6. Conclusions
7. Outlook
© Holst Centre
Roll to roll inkjet printing
Printer: SPG inkjet printer
Print head: Xaar 1001
Material: Sun Chemical EMD5603
Foil: Agfa PET, 125 µm
Print speed: 10 m/min
Outlook processing
Printing Flexible Electronics for health care Applications, Pit Teunissen
Movie: R2R Inkjet printing and sintering
Sintering module
NIR dryer
60% Power
Photonic sintering
2 lamps used;10Hz, 60% intensity
© Holst Centre
System in foil solution
Tutorial Hybrid Electronics – LOPEC 2014 (Munich) 26/05/2014
Storeskin
• shelve can detect spatially resolved presence of objects
• done by integration of a ‘large area pressure sensing foil’
• Only digital signals to outside world: more reliable
© Holst Centre
Skinpatch
• Wearable health application
• Demonstrated to work with monitoring skin temperature, humidity and movement
© Holst Centre
User interface design conference, April 1, 2014
Health patch
• Screen printed electrodes
• Disposable patch, reuse of electronics
• Stretchable electrodes for comfort
© Holst Centre
User interface design conference, April 1, 2014
Multi-functional printed sensor
• Sweat sensor
• Sensor measures ions (sodium, chloride); measure for dehydration
• More functionalities are under development
Pain relieve bandage
• For RSI patients
• Wearable electronics
• Stretchable and conformable printed circuit
• Integrated LED’s
© Holst Centre
Printing Flexible Electronics for health care Applications, Pit Teunissen
Outlook application Storeskin
• shelve can detect spatially resolved presence of objects
• done by integration of a ‘large area pressure sensing foil’
• electronics external, hidden in box
• Luxury chocolate box with integrated light sensor and LED’s
• Upon opening the box, the light sensor activates the LED’s
• LED’s reveal location of origin of the chocolate
local printing company started doing explorative work on printed electronics after attending several workshops on this topic by Holst Centre and TNO
Thank you for your attention!